The World Health Organization says millions of premature deaths can be prevented each year by reducing short lived climate pollutants. A WHO report recommends cutting emissions of black carbon, ozone and methane.

Carbon dioxide is the main greenhouse gas that causes global warming. But black carbon or soot, and methane and ozone in urban smog, all contribute to climate change and are harmful to health.

The World Health Organization says emissions from short-lived climate pollutants cause cardiovascular and respiratory diseases, including heart disease, pulmonary disease, respiratory infections and lung cancer. It says they are responsible for many of the more than seven million premature deaths each year linked to air pollution.

The WHO says the pollutants also can decrease agricultural yields.

WHO Environment Chief Maria Neira says the pollutants, which exist both outdoors and indoors, have a strong impact on climate change. But the good news, she says, is they only remain in the atmosphere for a few days to 10 years, compared to carbon dioxide, which can persist for hundreds, even thousands of years.

“The fact that they are short-lived pollutants, when you address them, you can reduce emissions very rapidly and then improve both air quality as well as slowing the rate of near term climate change ... You will have an immediate reduction in the ill-health and diseases caused by the reduction of air pollution,” said Neira.

The WHO has come up with a number of available, affordable measures to mitigate short-lived climate pollutants. Topping the list is reducing vehicle emissions by implementing higher emissions and efficiency standards.

Indoor air pollution is another source of ill health and premature death. The WHO reports about 2.8 billion low-income households rely on dirty fuels, such as coal, wood and kerosene for cooking and heating. It says cleaner and more efficient stove and fuel alternatives could reduce the health risks.